LOD script

[Bonedaddy]

Here's what I got so far, that gets the distance between camera and another object. It's set to pCube1 for tests. I realize it's probably fairly inelegant, but I'm thrilled it even works... :)

float $camPos[3]=`xform -q -t persp`;
float $objPos[3]=`xform -q -t pCube1`;
float $distx=$camPos[0]-$objPos[0];
float $disty=$camPos[1]-$objPos[1];
float $distz=$camPos[2]-$objPos[2];
vector $distance=<<$distx, $disty, $distz>>;
float $magnitude=mag($distance);

[Bonedaddy]

Genius!
Well, not entirely. But I got it to work. What I ended up doing is setting up my scene so that all the trees have two copies, same name with _hi and _lo at the end of it. They are grouped together in a normal group.
All the lod'd groups, in turn, are grouped underneath a larger group, in this code known as group1.
This took me FOREVER to get going, but I am very pleased that it works. I'm sure it's incredibly rough, and has plenty of sloppy code, so if anyone has any suggestions, by all means, make em! I'd like to learn more, certainly!





proc float jpo_getDistance(string $object) {
string $jpo_camera="persp";
float $camPos[3]=`xform -q -t $jpo_camera`;
float $objPos[3]=`xform -q -t $object`;
float $distx=$camPos[0]-$objPos[0];
float $disty=$camPos[1]-$objPos[1];
float $distz=$camPos[2]-$objPos[2];
vector $distance=<<$distx, $disty, $distz>>;
float $magnitude=mag($distance);
return $magnitude;
}


proc jpo_lod_change() {
float $threshhold=50;
string $children[]=`listRelatives -c -type "transform" group1`;
int $i;
for ($i = 0; $i < size($children); $i++) { //iterate through groups of
string $resolutionarray[]=`listRelatives -c -type "transform" $children[$i]`;
int $j;
if (size($resolutionarray)) { //if the object inside bigGroup is a lod_group
for ($j = 0; $j < size($resolutionarray); $j++) {
string $buffer[];
tokenize $resolutionarray[$j] "_" $buffer;
float $distance=jpo_getDistance($resolutionarray[$j]);
print("Distance is " + $distance);
if ($distance>$threshhold) { //over threshhold, turn to low lod
if ($buffer[size($buffer)-1]=="lo") { //if this object is low resolution
setAttr ($resolutionarray[$j] + ".visibility") 1;
}
if ($buffer[size($buffer)-1]=="hi") { //if this object is high resolution
setAttr ($resolutionarray[$j] + ".visibility") 0;
}
}
else { //if under threshhold
if ($buffer[size($buffer)-1]=="hi") { //if this object is high resolution
setAttr ($resolutionarray[$j] + ".visibility") 1;
}
if ($buffer[size($buffer)-1]=="lo") { //if this object is low resolution
setAttr ($resolutionarray[$j] + ".visibility") 0;
}
}
}
}
}

}

[Bonedaddy]

Except, of course, it won't work on instances, because instances all share the same shape node. Gahh... how to turn off the visibility for just instances... maybe I can hide them...

[Bonedaddy]

Alright, so what I CAN do to hide instances is to give them each an individual grouping (i.e. another transform node controlling their visibility above the shape node and below the lod_group node, and below the bigGroup node). If I do that, it's going to get incredibly messy. All in the name of render times, I suppose...

[sbp]

That's pretty good, but you don't have to reinvent the wheel, at least in 4.5. I don't know if 5 is different. The lodGroup is still valid, it's just MR doesn't use it to establish visibility so all you need is something like this.

string $lg[] = `ls -type lodGroup`;
for ($a in $lg)
{
float $gv[] = `getAttr ($a + ".o")`;
string $gn[] = `listConnections -type transform $a`;
int $i;
for ($i = 0; $i < size($gn); $i++)
eval ("setAttr " + $gn[$i] + ".v " + $gv[$i] );
}

You may or may not have to adjust for a naming convention, it depends on how you work.

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